Update touch selection to only modify one selection point at a time.

content/browser/android/content_view_core_impl.h

Index: content/browser/android/content_view_core_impl.h
diff --git a/content/browser/android/content_view_core_impl.h b/content/browser/android/content_view_core_impl.h
index cfa424bce77f6997b69c8ac3531f9452098e242c..2d4f6a5f4ecc0adb546b527fbf93ee899ca06dcc 100644
--- a/content/browser/android/content_view_core_impl.h
+++ b/content/browser/android/content_view_core_impl.h
@@ -274,8 +274,10 @@ class ContentViewCoreImpl : public ContentViewCore,
   void AttachLayer(scoped_refptr<cc::Layer> layer);
   void RemoveLayer(scoped_refptr<cc::Layer> layer);
 
-  void SelectBetweenCoordinates(const gfx::PointF& start,
-                                const gfx::PointF& end);
+  void MoveRangeSelectionExtent(const gfx::PointF& extent);
+
+  void SelectBetweenCoordinates(const gfx::PointF& base,
+                                const gfx::PointF& extent);
 
  private:
   class ContentViewUserData;